The goal of this K01 Mentored Career Award application is to advance Dr. Roan's career through research experiences, scholarly activities, training, and collaborative efforts. This will enable her to establish a sound Biomedical Research Program in Lung Health and Physiology at the University of Memphis (U of M), a diverse institution in an urban environment. More specifically, Dr. Roan will develop expertise in lung physiology and air-fluid barrier functionality through a robust set of activities that investigate alveolar permeability that will enable transition from an investigator with a background in soft tissue mechanics and mechanobiology to an independent researcher focused on acute lung injury. The proposed research focuses on acute respiratory distress syndrome, a devastating condition characterized in part by the presence of protein rich edema in the alveolar airspaces. Because clearance of edema is critical to resolution of the disease, strategies directed toward protecting the epithelial barrier and promoting epithelial repair are needed. The central hypothesis is that tumor necrosis factor-? (TNF-?) induces an increase in cytoskeletal tension within the alveolar epithelial cells making them more susceptible to barrier dysfunction and cell detachment caused by stretch through c-Jun NH2 kinase- (JNK-) mediated phosphorylation of zonula occludens 1 (ZO-1). In Aim 1, Dr. Roan will show that TNF-? and stretch will lead to much more cell detachment than either stimulus alone due to an increase in cell stiffness. Aim 2 will show that the increase in stiffness and barrier dysfunction are dependent on ZO-1 phosphorylation through JNK. In Aim 3, a multi- scale finite element model will be developed to predict how changes in junctional stress caused by TNF-? can lead to increased barrier dysfunction in vivo. Overall, this project will elucidate how early exposure of alveolar epithelial cells to TNF-? prior to mechanical ventilation induces cytoskeletal remodeling and alters the biophysical forces at the tight junctions leading to more injury. The candidate will be mentored by well- established investigators, with Dr. C.M. Waters, Professor and Vice Chair, Physiology, University of Tennessee Health Science Center (UTHSC) serving as the lead mentor. Dr. R.K. Rao and Dr. E. Fitzpatrick will guide the tight-junction biology and immunology aspects, respectively. Training activities will take place at both the University of Memphis and the UTHSC, partner institutions separated by an approximately 10 minute drive and synergistically pursuing biomedical research through a range of inter-campus activities. The UofM has agreed to allocate 75% of Dr. Roan's effort, and both the UofM and the UTHSC have agreed to provide access to curricular and laboratory facilities as needed to carry out the proposed 5-year mentored research and career development project for Dr. Roan to advance her career and establish a sound research program here at the U of M.